The purpose of this study is to determine the mechanisms that account for differences in bone and mineral metabolism and the lower incidence of osteoporosis and fractures in blacks, whether reduction of the rate of skel al remodeling in blacks is associated with decreases in bone resorption and is caused by diminished production or function of osteoclasts, whether there i skeletal resistance to parathyroid hormone, whether there are differences i skeletal production of growth factors and the influence of menopause and ag g in blacks.